BugTraq
AST-2017-012: Remote Crash Vulnerability in RTCP Stack Dec 13 2017 05:40PM
Asterisk Security Team (security asterisk org)
Asterisk Project Security Advisory - AST-2017-012

Product Asterisk
Summary Remote Crash Vulnerability in RTCP Stack
Nature of Advisory Denial of Service
Susceptibility Remote Unauthenticated Sessions
Severity Moderate
Exploits Known No
Reported On October 30, 2017
Reported By Tzafrir Cohen and Vitezslav Novy
Posted On December 13, 2017
Last Updated On December 12, 2017
Advisory Contact Jcolp AT digium DOT com
CVE Name

Description If a compound RTCP packet is received containing more than
one report (for example a Receiver Report and a Sender
Report) the RTCP stack will incorrectly store report
information outside of allocated memory potentially causing
a crash.

For all versions of Asterisk this vulnerability requires an
active call to be established.

For versions of Asterisk 13.17.2, 14.6.2, 15.0.0,
13.13-cert6 and greater an additional level of security is
placed upon RTCP packets. If the probation period for
incoming RTP traffic has passed any received RTCP packets
must contain the same SSRC as the RTP traffic. If the RTCP
packets do not then they are dropped. This ensures other
parties can not inject RTCP packets without they themselves
establishing an active call.

Resolution The RTCP stack has been changed so the report information is
always stored in allocated memory. The provided patches can
be applied to the appropriate version or the latest version
of Asterisk can be installed to receive the fix.

Affected Versions
Product Release Series
Asterisk Open Source 13.x All Versions
Asterisk Open Source 14.x All Versions
Asterisk Open Source 15.x All Versions
Certified Asterisk 13.13 All Versions

Corrected In
Product Release
Asterisk Open Source 13.18.4, 14.7.4, 15.1.4
Certified Asterisk 13.13-cert9

Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2017-012-13.diff Asterisk
13
http://downloads.asterisk.org/pub/security/AST-2017-012-14.diff Asterisk
14
http://downloads.asterisk.org/pub/security/AST-2017-012-15.diff Asterisk
15
http://downloads.asterisk.org/pub/security/AST-2017-012-13.13.diff Certified
Asterisk
13.13

Links https://issues.asterisk.org/jira/browse/ASTERISK-27382

https://issues.asterisk.org/jira/browse/ASTERISK-27429

Asterisk Project Security Advisories are posted at
http://www.asterisk.org/security

This document may be superseded by later versions; if so, the latest
version will be posted at
http://downloads.digium.com/pub/security/AST-2017-012.pdf and
http://downloads.digium.com/pub/security/AST-2017-012.html

Revision History
Date Editor Revisions Made
November 30, 2017 Joshua Colp Initial Revision

Asterisk Project Security Advisory - AST-2017-012
Copyright © 2017 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.

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